page_title: National Science Foundation Network
section_title: 56 kbit/s backbone
hierarchical_section_title: National Science Foundation Network / History / 56 kbit/s backbone
caption_attribution_description: English: NSFNET T1 Backbone and Regional Networks Traffic, 1991 This image is a visualization study of inbound traffic measured in billions of bytes on the NSFNET T1 backbone for the month of September 1991. The traffic volume range is depicted from purple (zero bytes) to white (100 billion bytes). It represents data collected by Merit Network, Inc. Visualization by Donna Cox &amp; Robert Patterson, National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign. Sources: Merit Network, Inc., NCSA, and the National Science Foundation. URLs: http://www.merit.edu/networkresearch/projecthistory/nsfnet/nsfnet_maps.php http://avl.ncsa.illinois.edu/project-archive/visualizing-the-early-internet http://www.nsf.gov/news/mmg/media/images/nsfnet_h1.jpg
context_page_description: The National Science Foundation Network was a program of coordinated, evolving projects sponsored by the National Science Foundation from 1985 to 1995 to promote advanced research and education networking in the United States. The program created several nationwide backbone computer networks in support of these initiatives. Initially created to link researchers to the NSF-funded supercomputing centers, through further public funding and private industry partnerships it developed into a major part of the Internet backbone.
  The National Science Foundation permitted only government agencies and universities to use the network until 1989 when the first commercial Internet service provider emerged. By 1991, the NSF removed restrictions on access and the commercial ISP business grew rapidly.
context_section_description: The NSFNET initiated operations in 1986 using TCP/IP. Its six backbone sites were interconnected with leased 56-kbit/s links, built by a group including the University of Illinois National Center for Supercomputing Applications (NCSA), Cornell University Theory Center, University of Delaware, and Merit Network. PDP-11/73 minicomputers with routing and management software, called Fuzzballs, served as the network routers since they already implemented the TCP/IP standard.
  This original 56 kbit/s backbone was overseen by the supercomputer centers themselves with the lead taken by Ed Krol at the University of Illinois at Urbana–Champaign. PDP-11/73 Fuzzball routers were configured and run by Hans-Werner Braun at the Merit Network and statistics were collected by Cornell University.
  Support for NSFNET end-users was provided by the NSF Network Service Center (NNSC), located at BBN Technologies and included publishing the softbound "Internet Manager's Phonebook" which listed the contact information for every issued domain name and IP address in 1990. Incidentally, Ed Krol also authored the Hitchhiker's Guide to the Internet to help users of the NSFNET understand its capabilities. The Hitchhiker's Guide became one of the first help manuals for the Internet.
  As regional networks grew the 56 kbit/s NSFNET backbone experienced rapid increases in network traffic and became seriously congested. In June 1987 NSF issued a new solicitation to upgrade and expand NSFNET.
caption: NSFNET Traffic 1991, NSFNET backbone nodes are shown at the top, regional networks below, traffic volume is depicted from purple (zero bytes) to white (100 billion bytes), visualization by NCSA using traffic data provided by the Merit Network.
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